Data storage tape devices with multiple heads generally utilize methodologies that rely on the limiting margins of the data track layout on the media to prevent off-track (OT) writing of data to the media. Such limiting margins determine OT thresholds, which are monitored by a servo subsystem of the tape device that controls the common motion of the multiple heads. Using such thresholds, the servo subsystem prevents the read/write channel of the device from writing data tracks too close to each other on the media. Writing of data to the media commences, continues or resumes only if and when the servo subsystem is capable of moving the recording heads within the allowed thresholds.
Present multiple head designs in these tape devices include a rigid body housing and actuating structure. As a result, in the event of excessive external disturbances to the heads or excessive instantaneous lateral motion of the tape media, all heads move away from the center of their corresponding tracks and beyond the OT threshold limits. In such circumstances, servo off-track functionality normally invokes the buffering of data streaming to the heads and prevents the heads from processing and recording that streaming data on the tape media until all heads are moved back to within their OT threshold limits.
Tape devices with very high track densities, such as optical tape drives, inherently have extreme and stringent requirements on off-track threshold margins and limits. As a result, the performance limitations described above resulting from excessive external disturbances to the heads or excessive instantaneous tape lateral motion can have significant adverse impact on data capacity and transfer rate of such tape devices.
Thus, there exists a need for an improved system and method for off-track write prevention and data recovery in an optical tape drive having multiple optical heads. Such a system and method would overcome performance limitations associated with excessive external disturbances to optical heads or excessive instantaneous tape lateral motion to provide greater data transfer rates overall and increased data capacity.